2. Net sales

EUR 1,000 2016 2015



Revenue from contract work recognised by stage of completion (IAS 11) 19,667 23,496
Revenue from maintenance and support (IAS 18) 28,947 31,138
Revenue from goods and services (IAS 18) 11,060 19,433
Currency exchange gains and losses 402 2,395
Net sales total 60,075 76,462



Order book for contract work 12,742 15,361
Order book for maintenance and support, goods and services 12,112 11,422
Order book total 24,854 26,783



Projects in progress:

Cumulative revenue recognised for projects in progress 15,050 38,389
Cumulative invoicing for projects in progress recognised by stage of completion 14,651 21,720
Accrued income related to construction contracts, work in progress 399 16,669



Aggregate amount of costs incurred for projects in progress 4,372 21,072



On the reporting date, the Group has no retentions held by customers. The Group has not received any advances related to projects in progress.